Flame retardant composition for textiles

ABSTRACT

THE FLAME RETARDANCY OF TEXTILE FABRICS IS ENHANCED THROUGH TREATMENT WITH A COMPOSITION COMPRISING AN AZIRIDINYL PHOSPHINE OXIDE OR SULFUDE AND A PHOSPHORIC AMIDE SUCH AS PHOSPHORIC TRIAMIDE.

nitd States Patent 3,712,739 Patented Jan. 23, 1973 3,712,739 FLAME RETARDANT CGMiOSITlON FOR TEXTILES Roger t3. Linderman and Charles D. Cline, Charlotte, N.C., assignors to Story Chemical Corporation, Athens, Ga. No Drawing. Continuation-impart of application Ser. No. 17,894, Mar. 9, 1970, now Patent No. 3,640,823, dated Feb. 8, 1972. This application Jan. 3, 1972, Ser. No.

Int. Cl. D06rn /64, 13/26, 13/44 US. Cl. 3-116 P 14 Claims ABSTRACT OF THE DISCLOSURE The flame retardancy of textile fabrics is enhanced through treatment with a composition comprising an aziridinyl phosphine oxide or sulfide and a phosphoric amide such as phosphoric triamide.

This application is a continuation-in-part of pending application Ser. No. 17,894, filed Mar. 9, 1970, now Pat. N0. 3,640,823.

The invention of this application is as indicated a flame retardant composition. When applied to textile fabrics it is effective to render those fabrics resistant to burning. The invention is particularly applicable to cellulosic fabrics.

Many fire-retardant compositions have in the past been applied to textile fabrics which then intumesce or form a cellular char when exposed to a direct flame or high temperature. Many of these compositions are water-soluble tnd treated fabrics produced from such composition, while satisfactory for limited purposes, have proven to be somewhat unsatisfactory when they are subjected to frequent washings or conditions of high humidity, because the Water-soluble materials are leached out of the fabric under such conditions and the fabric loses its fire-retardant properties. In efforts to avoid these shortcomings, thermosetting resins such as urea-formaldehyde resins have been used to give some permanency to the fire-retardant treatment and thus protect the substrate as well as provide an ornamental finish thereon. These thermosetting resins, however, have the disadvantage of becoming brittle when they are highly polymerized with the result that the treated fabric is stiff and has reduced resistance to abrasion; furthermore, the flame retardance is not satisfactory.

Other fire-retardant compositions have not been entirely satisfactory because the amount of add-on required to provide the desired degree of flame retardancy is very high, i.e., in some cases as much as 30 or 40% of the fire-retardant composition based on fabric weight must be incorporated into the fabric to render the fabric fireretardant. This makes the process costly, of course, and also it usually gives the fabric a poor hand.

The desirability of rendering textile fabrics resistant to fire and burning is evident. Bedding, upholstery and drapery fabrics are of particular interest in this regard, but the advantages of fire-proofing wearing apparel likewise are manifest. Fire-proof night Wear, for example, represents a very desirable goal. Many fires, in the some or in public gathering places, begin with an unnoticed burning cigarette which ignites bedding, curtains, or drapers which in turn spread the fire to other more diflicultly burnable materials such as wood. The use of fire-retardant fabrics in these instances undoubtedly would diminish the number of serious fires very significantly, because the fire would burn out before it has a chance to reach serious proportions.

In accordance with the terminology which has been developed in this field fire retardancy results from the treatment of a substrate such as a textile fabric with various chemicals so that it becomes resistant to the propagation of flame across its surface after the igniting flame has been removed; that is, a fire retardant material Will not support combustion independently of an external source of heat. In contact with an open flame, however, or at elevated temperatures, fire-retardant cellulosic material can be expected to char and decompose.

The treated textile fabrics of the present invention have a high degree of fire retardancy while at the same time retaining to a large extent the original hand of the untreated textile fabrics. The color, physical appearance, strength and softness of the fabric are not substantially affected by such treatment.

It is accordingly a principal object of the present invention to provide fire-retardant compositions.

It is a further object of the present invention to provide fire-retardant compositions which are effective at relatively low add-on concentrations.

It is a further object of the present invention to provide fire-retardant fabrics.

It is a further object of the present invention to provide fire-retardant fabrics which retain their fire retardancy after repeated launderings and dry cleanings.

It is a further object of the present invention to provide fire-retardant fabrics which have a good hand.

It is a further object of the present invention to provide fire-retardant fabrics which are strong and resistant to abrasion.

It is a further object of the present invention to provide a process for imparting fire retardancy to new fabrics.

These and other objects are accomplished by a fireretardant composition comprising an aziridinyl phosphine oxide or sulfide and a phosphoric amide. These ingredients are soluble or readily dispersible in water and they are ordinarily applied to a fabric from an aqueous solution. A fabric thus treated is characterized by a high degree of flame resistance.

The phosphoric amide may be any of several such compounds conforming to the structure:

where R is a lower alkyl group or hydrogen, A is NH NHR or R0, B is NH NHR or R0, and X is oxygen or sulfur. Specific illustrations of suitable phosphoric amides include phosphoric triamide, thiophosphoric amide, methyl phosphoric diamide, ethyl thiophosphoric diamide, diethyl phosphoramide and the N-methyl, N-ethyl etc. analogs thereof. The lower alkyl group may contain up to four carbon atoms, i.e., it may be methyl, ethyl, propyl or butyl.

Phosphoric triamide is preferred. It may be prepared by the reaction of anhydrous ammonia with phosphorus oxychloride in an inert solvent such as chloroform. The stoichiometry of the reaction involves one mole of phosphoric oxychioride and 6 mols of ammonia. The product mixture includes not only the desired phosphoric triamide, but also ammonium chloride. The ammonium chloride may be removed by reaction with diethylamine to form diethylamine hydrochloride and ammonia. The ammonia evolves from the product mixture and the diethylamine hydrochloride may be removed by washing with chloroform. The reaction is illustrated by the following equation:

The phosphoryl triamide is a white solid, soluble in cold water.

The aziridinyl phosphine oxide or sulfide usually is prepared by reaction of phosphorous oxychoride or thiophosphoryl chloride with an alkyleneimine such as ethyleneimine. This reaction is illustrated, in the preparation of tris-aziridinyl phosphine oxide, by the following equation:

The above equation shows the formation of tris-aziridinyl phosphine oxide, which is preferred for the purposes of this invention, but mono-aziridinyl and di-aziridinyl phosphine oxides as well as the mono-, diand tris-aziridinyl sulfides likewise are contemplated for these purposes. Propyleneimine and other lower (up to 4 carbon atoms) alkyleneimines may be used instead of ethyleneimine in the preparation of this ingredient.

As indicated, the ingredients of the fire-retardant compositions ordinarily are soluble in water and ordinarily are applied to textile fabrics from an aqueous solution. Where one or both of the ingredients are not readily soluble in water a small proportion of dioxane or similar water miscible, inert solvent may be added to solubilize these ingredients in the aqueous solution. The relative proportions of ingredients which may be used are from about 1 to about 10 parts (molar) of aziridinyl phosphine oxide or sulfide and from about 1 to about 10 parts (molar) of phosphoric amide. Preferably, the aqueous solution will contain from about 0.5 to about 4 parts, on a molar basis, of phosphoric amide per part of aziridinyl phosphine oxide or sulfide.

The above aqueous solution may also contain a latent acid catalyst such as zinc chloride, zinc nitrate or magnesium chloride which serves to promote the reaction of the phosphoric amide and aziridinyl phosphine oxide or sulfide with each other and with the textile fabric during the curing step. Residual ammonium chloride from the phosphoric amide product mixture will also serve such purpose. The catalyst, when used, should be present in a concentration of from about 0.1 to 10% based on the weight of the fire-retardant solution. The temperature of the treating bath is conveniently within the range of from about 10 C. to about 35 C.

The flame retardant compositions herein are preferably applied to a fabric by immersing the fabric in an aqueous solution of from about 1% to about 30% by weight of the flame retardant composition, then passing it through a squeeze roller. Multiple immersions and/or squeezing can be effected if necessary to achieve the desired application on the fabric. Ordinarily, from about 50% to about 100% by weight of flame retardant solution based on the weight of the fabric is thus applied. The fabric is then dried at elevated tempertaure, i.e., from about 75 C. to about 125 C., then cured by heating at a temperature within the range of from about 125 C. to about 250 C. The time of curing will vary depending upon the temperature, i.e., less time is required to cure at 250 C. than is required to cure at 125 C. After the curing step, the amount of dry flame retardant composition deposited on the fabric is from about 5% to about 25% by weight of the fabric. In many instances, the flame retardant compositions are applied as aqueous emulsions which also contain polymeric materials such as polyvinyl acetate (as a hind builder), an acrylic latex, polyethylene and the like. Many different polymeric materials are commonly used in the treatment of textile fabrics and these may, in general, be applied together with the flame retardant compositions herein, in aqueous emulsion, or they may be applied separately. Other methods of applying the flame retardant composition to the fabric may be employed, e.g., spraying, brushing on, sprinkling, etc.

If desired, softening agents may be introduced into the flame retardant solution, or alternatively, any softening step may be postponed until after the treated fabric has been cured. The softening step results in a softer, more desirable hand. The softening agent may be applied by any of the conventional techniques. Suitable textile softening agents include polyethylene emulsion, ethylene glycol distearate and the like. The concentration of the softening agent ordinarily is from about 0.2% to about 5%.

The invention is illustrated by the following examples which are not to be taken as limiting in any respect. All parts and percentages are by weight unless otherwise expressly stated.

EXAMPLE I An square cotton cloth is immersed in an aqueous solution of 9% (0.05 molar part) of tris-aziridinyl phosphine oxide and 12% (0.13 molar part) of phosphoric triamide, then passed between rubber squeeze rollers to a drip-dry state. The quantity of aqueous solution thus imparted to the cotton fabric is 70% based on the weight of the fabric. The fabric is dried at C. and cured for 2 minutes at 160 C. After Washing (to remove excess flame retardant ingredients) and drying, the treated fabric shows a 10% weight increase and a char length of 2.5 inches, determined in accordance with the AATCC Test Method No. 34-1969. This test is carried out as follows:

A test sample of the fabric, 2% in. x 10 in., is placed in the flame of a Bunsen burner for 12.0 seconds, then withdrawn and allowed to glow and smolder until it extinguishes itself. The sample then is torn under standard con: ditions, through the charred area and the length of the tear is taken as a measure of fire-retardance, i.e., the less the length of tear the more fire-retardant is the sample. A sample fabric with relatively poor flame retardancy will burn along its entire length and be rated BEL (burn entire length).

After 20 full-cycle launderings at F. in a hometype washing machine, the treated fabric of this example showed a char length of 3.5 inches, indicating that the flame retardant composition is sufficiently attached to the fabric that it does not wash out on laundering.

EXAMPLE II An 80 square cotton fabric is immersed in an aqueous solution of 7% (0.04 molar part) of tris-aziridinyl phosphine oxide and 12% (0.13 molar part) of phosphoric triamide, then passed through rubber squeeze rollers to a drip-dry state. The increase in weight of the cotton fabric is 70%. The fabric is then dried at 105 C. and cured for 2 minutes at C. After washing (to remove excess flame retardant ingredients) and drying, the treated fabric shows a 10% weight increase and a char length of 2.5 inches, measured in accordance with the above AATCC test.

EXAMPLE III The effectiveness of the flame retardant compositions herein when applied to different types of fabric is shown in the table of data below. It will be noted that while cotton is apparently more susceptible to virtually permanent improvement with respect to flame retardance, other cel1ulosics are also very much improved in this regard. In each instance, the flame retardant composition was applied as in the previous examples and the treated fabric dried at 90 C., then cured at 154 C. for 90 seconds. The washings were as above full-cycle launderings at 140 F. in a home-type washing machine.

Other properties of a fabric are of course affected by the treatment herein. Wrinkle recovery, for example, is improved. Results of AATCC Test 16-1968 showed an increase in recovery angle for each of the treated cotton fabrics in the above table. Tear strength (determined by the Elmendorf Tear Test) and tensile strength determined by ASTM Test D39-49) are diminished somewhat, but to a much lesser degree than treatment with conventional durable press finishes.

The flame retardant compositions of this invention are effective on a variety of fabrics and especially so on cellulosic fabrics. Cotton and rayon are benefited most by the application of these materials, and fabrics of mixed content having at least about 65% of a cellulosic material, e.g., cotton or viscose rayon, are also very much improved. The fabrics may be Woven, non-woven or knitted.

A notable feature of the invention herein is the effectiveness of treatment at low add-on concentration. At a level of 12% add-on the flame retardant compositions of this invention are superior to those of the prior art at much higher levels of add-on. A typical prior art flame retardant composition, for example, when used at 27% add-on showed a char length of 2 /2 inches, but after five launderings it was rated BEL.

While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modifications and this application is intended to cover any variations, uses, or adaptations of the invention, following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth and as fall within the scope of the invention and the limits of the appended claims.

What is claimed is:

1. A method for imparting flame retardancy to a cellulosic textile fabric comprising contacting a cellulosic textile fabric with an aqueous mixture containing from about 1% to about 30% of a fire-retardant composition comprising from about 1 to about 10 parts on a molar basis, of an aziridinyl phosphine oxide or sulfide and from about 1 to about 10 parts of phosphoric triamide and curing the fabric by heating it.

2. The method of claim 1 wherein the textile fabric comprises cotton.

3. The method of claim 1 wherein the textile fabric is cotton.

4. The method of claim 1 wherein the textile fabric is viscose rayon.

5. The method of claim 1 wherein the fire-retardant composition comprises from about 0.5 to about 4 parts,

on a molar basis, of an aziridinyl phosphine oxide or sulfide per part of phosphoric triamide.

6. The method of claim 1 wherein the aziridinyl phosphine oxide or sulfide is a tris-aziridinyl phosphine oxide.

7. A method for imparting flame retardancy to a cellulosic textile fabric comprising contacting a cellulosic textile fabric with an aqueous mixture containing from about 1% to about 30% of a fire-retardant composition comprising from about 1 to about 10 parts, on a molar basis, of a tris-aziridinyl phosphine oxide and from about 1 to about 1 0 parts of phosphoric triamide, drying the thus treated fabric, and curing it by heating at a temperature within the range of from about 125 C. to about 250 C.

8. The method of claim 7 wherein the fire-retardant composition comprises from about 0.5 to about 4 mols of phosphoric triamide per mol of tris-aziridinyl phosphine oxide.

9. The method of claim 7 wherein the tris-aziridinyl phosphine oxide conforms to the molecular structure References Cited UNITED STATES PATENTS 3,640,823 3/1970 Lindcrman et al. 2528.1

GEORGE F. LESMES, Primary Examiner J. C. CANNON, Assistant Examiner U.S. Cl. X.R.

8ll5.6, 116.2, 117-136, 139.5, 143 R; 106- 15 PP; 252-81; 2602 P, Dig. 24 

